SURVEY OF NEARBY FGK STARS AT 160 μm WITH SPITZER

The Spitzer Space Telescope has advanced debris disk science tremendously with a wealth of information on debris disks around nearby A, F, G, K and M stars at 24 and 70 μm with the MIPS photometer and at 8-34 μm with IRS. Here we present 160 μm observations of a small sub-set of these stars. At this wavelength, the stellar photospheric emission is negligible and any detected emission corresponds to cold dust in extended Kuiper belt analogs. However, the Spitzer 160 μm observations are limited in sensitivity by the large beam size which results in significant “noise” due to cirrus and extragalactic confusion. In addition, the 160 μm measurements suffer from the added complication of a light leak next to the star’s position whose flux is proportional to the near-infrared flux of the star. We are able to remove the contamination from the leak and report 160 μm measurements or upper limits for 24 stars. Three stars (HD 10647, HD 207129, and HD 115617) have excesses at 160 μm that we use to constrain the properties of the debris disks around them. A more detailed model of the spectral energy distribution of HD 10647 reveals that the 70 and 160 μm emission could be due to small water ice particles at a distance of 100 AU consistent with Hubble Space Telescope optical imaging of circumstellar material in the system.